/*

 * Licensed to the Apache Software Foundation (ASF) under one

 * or more contributor license agreements.  See the NOTICE file

 * distributed with this work for additional information

 * regarding copyright ownership.  The ASF licenses this file

 * to you under the Apache License, Version 2.0 (the

 * "License"); you may not use this file except in compliance

 * with the License.  You may obtain a copy of the License at

 *

 *     http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */

package com.bff.gaia.unified.sdk.transforms.windowing;



import com.bff.gaia.unified.sdk.annotations.Experimental;

import org.joda.time.Instant;



import java.util.List;



/**

 * A trigger that is equivalent to {@code Repeatedly.forever(AfterWatermark.pastEndOfWindow())}. See

 * {@link Repeatedly#forever} and {@link AfterWatermark#pastEndOfWindow} for more details.

 *

 * <p>This is a distinguished class to make it easy for runners to optimize for this common case.

 */

@Experimental(Experimental.Kind.TRIGGER)

public class DefaultTrigger extends Trigger {



  private DefaultTrigger() {

    super();

  }



  /** Returns the default trigger. */

  public static DefaultTrigger of() {

    return new DefaultTrigger();

  }



  @Override

  public Instant getWatermarkThatGuaranteesFiring(BoundedWindow window) {

    return window.maxTimestamp();

  }



  @Override

  public boolean isCompatible(Trigger other) {

    // Semantically, all default triggers are identical

    return other instanceof DefaultTrigger;

  }



  @Override

  protected Trigger getContinuationTrigger(List<Trigger> continuationTriggers) {

    return this;

  }

}